The contractor will obtain biopsy of surgical specimens, together with appropriate clinical and pathological documentation, and establish and characterize tumor cell lines. Characterization will include demonstration that the cell line is free of contamination with adventitious agents, of human origin, tumorigenic in athymic mice, and retains features of the tumor of origin. In addition, the contractor will evaluate the relative suitability of candidate cell lines with respect to assay methodology in use for primary screening and make recommendations for selection of cell lines for use in a breast cancer cell line panel. The purpose of this contract is to establish a focused effort aimed at development and characterization of new human breast carcinoma cell lines for use in the DTP antitumor drug screening project.